[ adding netdev so others can chime in ] On 7/10/19 2:28 AM, Jan Szewczyk wrote: > Hi guys! > > We can see different behavior of one of our commands that supposed to > show pmtu information. > > It’s using netlink message RTM_GETROUTE to get the information and in > Linux kernel version 4.12 after sending big packet (and triggering > “packet too big”) there is an entry with PMTU and expiration time. > > In the version 4.18 unfortunately the entry looks different and there is > no PMTU information.
Can you try with 4.19.58 (latest stable release for 4.19)? Perhaps there was a bugfix that is missing from 4.18. The kernel has 2 commands under tools/testing/selftests/net -- pmtu.sh and icmp_redirect.sh -- that verify exceptions are created and use 'ip ro get' to verify the mtu. > > I can see that in your commit > https://github.com/torvalds/linux/commit/d4ead6b34b67fd711639324b6465a050bcb197d4, > these lines disappeared from route.c: > > > > if (rt->rt6i_pmtu) > > metrics[RTAX_MTU - 1] = rt->rt6i_pmtu; > > > > I’m very beginner in linux kernel code, can you help me and tell me if > that could cause this different behavior? > > > > > > BR, > > Jan Szewczyk >
